Chap. 7J 



GRAVITATIONAL METHODS 



235 



treated as cylindrical and not as spherical shells; hence, in any azimuthal 

 section their outlines are rectangles. ^"^ The effect of the segments depends 

 on their angular opening and varies with the number of azimuths (eight, 

 sixteen, thirty-two, and so on) in which the diagrams are to be used. 

 The azimuthal effect is then considered by relations resembling formula 



6 (iradifnO Diagrams 



v^P^^r^^^^ 



^^6^ii»W^ 



'yi 



C (Curvttfurt) Diaframs 



^^^viHoiv^a^ 



^^oVl_Hor^^ 



Fig. 7-84. Application of vertical diagrams. 



(7-76). The number of elements between horizon and terrain profile are 

 substituted for the elevations h. Two diagrams are required, one for 

 gradients and the other for curvature values. In a modification of 

 Haalck's method by Gassmann^"* the effects obtained by the evaluation 



1"' See also H. Haalck, Die Gravimetrischen Methoden der Angewandten Geophysik, 

 pp. 116 and 117 (1929). 



1" Beitr. angew. Geophys., 6(2), 202 (1936). 



